Oxalic acid derivatives

ABSTRACT

Ultraviolet light absorbers for plastics (for example polyolefins, e.g. polyethylene or polypropylene; polyvinylchloride; or a nitro lacquer), which may be incorporated with or without one or more other known ultraviolet light stabilizers into the plastics, have the formula I   in which each of R1, R2, R3, R4, R5, R6, R7 and R8 represents H, Cl, Br, -CnH2n 1, -CnH2n 1 or -O-CnH2n 1 or an -O-aryl, aryl, aralkyl or alkaryl radical with up to eight carbon atoms, M REPRESENTS A WHOLE NUMBER FROM 1 TO 8 INCLUSIVE, AND N REPRESENTS A WHOLE NUMBER FROM 1 TO 4 INCLUSIVE, WITH THE PROVISO THAT THE RADICALS R1, R2, R3, R4, R5, R6, R7 and R8, within their definition, may be similar or dissimilar and n need not necessarily have the same value in all of the radicals where n occurs, AND THE FORMULA Ia   WHEREIN EACH OF R1&#39;&#39; to R10&#39;&#39;, independently of one another, is selected from H, alkyl, aralkyl, alkaryl, alkyl-(OC2H4)n , alkyl-(OC3H6)n , Cl, Br, OH, O-alkyl, O-aryl, S-alkyl, S-aryl, COO-alkyl, COO-aryl, CONH-alkyl, CONH-aryl, NHCO-alkyl, NHCOaryl, alkyl ether radicals and alkyl thioether radicals, with the proviso that at least one of the radicals R&#39;&#39;1 to R&#39;&#39;10 must be such that at least one -C-S-C- grouping is present in the compound, and N&#39;&#39; REPRESENTS A WHOLE NUMBER OF FROM 1 TO 12 INCLUSIVE.

States tent 1 Enter et a1.

[451 Sept. 16, 1975 1 OXALIC ACID DERIVATIVES [75] Inventors: Kurt Hofer, Munchenstein; Rudolf Moesch, Stein; Alfred Schilli, Reinach, all of Switzerland; Evelyne Burdet, Mulhouse, France [73] Assignee: Sandoz Ltd., Basel, Switzerland [22] Filed: Sept. 7, 1973 [21] Appl. No.2 405,331

Related U.S. Application Data [63] Continuation-in-part of Ser. Nos. 170,660, Aug. 10, 1971, Pat. No. 3,808,273, and Ser, No. 808,041, March 12, 1969, abandoned, said Ser. No. 808,041, is a continuation-in-part of Ser. No. 799,898, Feb. 17, 1969, abandoned.

[30] Foreign Application Priority Data Feb. 19, 1968 Switzerland 2371/68 Mar. 12, 1968 Switzerland 3641/68 Aug. 13, 1970 Switzerland 12173/71 [52] U.S. Cl 260/558 S; 260/559 T; 260/559 A;

260/45.9 NC; 252/391; 252/392 [51] Int. Cl. C07C 103/30 [58] Field of Search .260/558, 559

[56] References Cited UNITED STATES PATENTS 3,529,982 9/1970 Luethi et a]. 260/559 FOREIGN PATENTS OR APPLlCATlONS 1,516,276 1/1968 France 260/559 Primary Examinerl-larry I. Moatz Attorney, Agent, or FirmGerald D. Sharkin; Richard E. Vila; Joseph J. Borovian [5 7 ABSTRACT Ultraviolet light absorbers for plastics (for example polyolefins, e.g. polyethylene or polypropylene; polyvinylchloride; or a nitro lacquer), which may be incorporated with or without one or more other known ultraviolet light stabilizers into the plastics, have the formula I in which each of R R R R R R R and R represents H, Cl, Br, -C,,H C,,H or OC,-,l-l or an Oaryl, aryl, aralkyl or alkaryl radical with up to eight carbon atoms,

m represents a whole number from 1 to 8 inclusive,

and

n represents a whole number from 1 to 4 inclusive, with the proviso that the radicals R R R R R R R and R within their definition, may be similar or dissimilar and 11 need not necessarily have the same value in all of the radicals where n occurs,

and the formula la 0 5 i i I l 5 R Of imcoco1m$ 12 l l i .2 1.

52 Claims, No Drawings OXALIC ACID DERIVATIVES This application is a continuation-in-part of our copending applications, Ser. No. 170,660, filed Aug. 10, 1971, now US. Pat. No. 3,808,273, and Ser. No. 808,041, filed Mar. 12, 1969; and now abandoned, said Ser. No. 808,041 being, itself, a continuation-in-part of application Ser. No. 799,898, filed Feb. 17, 1969, and now abandoned.

It is known that certain asymmetric diaryloxalamides may be used as UV light absorbers for plastics. The known compounds of this class, however, are either relatively difficultly soluble in the plastics, especially polyolefins, or alternatively contain one or more high molecular weight organophile radicals with a hydrocarbon portion containing more than eight carbon atoms which reduce the effectiveness of the diaryloxalamides as UV light absorbers.

It has now been found that asymmetric diaryloxalamide compounds of the formula I below have a good solubility in plastics, especially in polyolefins, which compounds do not contain any of the above mentioned high molecular weight organophile radicals in their molecule.

The present invention provides compounds of the formula I R5 R R5 R6 R2 NHCOCONH R7 I 1 m 2m+1 8 n 2n+l in which each of R,, R R R R R R and R represents H, Cl, Br, C,,II 'C,,H or -OC,,I-I or an Oaryl, alkaryl, aralkyl or aryl radical with up to eight carbon atoms, m represents'a whole number from 1 to 8 inclusive,

and n represents a whole number from I to 4 inclusive, with the proviso that the radicals R R R R R R R and R within their definition, may be similar or dissimilar and n need not necessarily have the same value in all of the radicals where n occurs. The present invention also provides a process for the production of the compounds of formula I, which process is characterized in that 1 mol of oxalic acid or 1 mol of a functional derivative (for example an ester, acid halide or ester halide, e.g. the acidchloride, acid bromide or an ester chloride) thereof is reacted, simultaneously or consecutively, with 1 mol of a compound of the formula II in which R; to R, are as defined above and x is zero or a whole number from 1 to 8 inclusive, and l mol of a compound of the formula III NR III in which R to R and n are as defined above, in such a way that amidation of the oxalic acid or its functional derivative is effected to the highest degree possible, and that the resulting product is alkylated with an alkylation agent containing the above radical C,,,H when said product contains a phenolic hydroxyl radical.

The compounds of formula I are very stable against the effect of heat, absorb UV light rays, and are easily soluble in plastics, especially polyolefins.

The present invention thus also provides a plastics, especially polyethylene or other polyolefin, structure containing dissolved therein a UV light stabilizer constituted by a compound of the formula I above. Preferably the amount of said compound I in said plastics structure should be from 0.l to 0.5% by weight. Furthermore, it is also within the scope of the present invention to add to the plastics with the dissolved UV light stabilizer of the formula I one or more additional UV light stabilizers, e.g. a nickel salt UV light stabilizer, a nickel complex UV light stabilizer or a sterically hindered phenol UV light stabilizer.

By means of two concrete cases, the following Examples 1 and 2 explain how the diaryloxalamides of the formula I may be produced, the temperatures being stated in degrees Centrigrade and the quantities in parts by weight. In Table 1, given after Examples 1 and 2, further compounds of formula I are listed which are produced in accordance with the method set forth in Example 1 or 2. The compounds of formula I as produced by the specifically described method may be incorporated in plastics without purification or may first be purified. Plastics containing a compound of formula I in an amount of from 0.1 to 0.5% by weight are protected against heat and especially against UV light rays; specifically pressed sheets of polyethylene containing such an amount of a compound of formula I are clear in appearance and protected against the harmful effect of UV light rays to an extent sufficient for practical purposes.

Examples A to D illustrate specific methods of using specified compounds of formula I. In Table 2 there are mentioned, for purposes of comparison, a number of diaryloxalamides and their properties which diaryloxalamides do not have the formula I and are therefore outside the scope of the present invention. In both Tables, E signifies the molar extinction coefficient. This was determined with light of a wave length lambda with an alcoholic solution of the oxalamide. Lambda is also the most strongly absorbed wave length expressed in ma.

The solubility of the oxalamides in ethyl alcohol and hard mass results which is first comminuted and subsebenzine (boiling point 100 to 120C, D =0.727) was quently triturated with alcohol in a trituration dish, sucdetermined at 20 to 22 in milligrams per litre. tioned off and washed with alcohol.

In the Examples reference is made to a Xenotest ap- The resulting crude product melts at 121 to 131. By paratus and to a Fadeometer; these are manufactured 5 recrystallization from benzene pure colourless by Atlas Electric Devices Company of Chicago 10, lllio-ethyloxy-o-ethyl-oxalic acid bis-anilide is obtained nois, U.S.A., the Fadeometer being sold under the deswith a melting point of 1 19 to 121 and a yield of about ignation Typ FOA-R Serie No. F0 2770. 65%.

EXAMPLE 1 I EXAMPLE 2 Production of o-ethoxy-o-ethyl-oxalic acid bis-anilide By using o-aminophenol instead of o-phenetidine in I NH 2 C H OOC-COOC H NTICOCOOC H 00 E OC H II {jkaracocooc r B N 0 @NhCOCONI-IQ OC H H 00 11 C 5 I. o-Phenetidine and oxalic acid diethyl ester are Example 1 there is obtained the compound of the formixed in molar ratio 1:2. About 3 to 4 ml, per mol of ula amine, of ethereal boron trifluoride as catalyst are added to the resulting mixture and heating while stirring is effected to a bath temperature of 130. After a NHCOCONH short time, dissolution takes place. When ethanol reflux commences, a vacuum (about 200 mm of Hg) is OH applied to the mixture so as to remove the ethanol and 2 5 stirring at the same temperature is continued for a further 1% hours. The resulting dark brown solution is 1 mol of thls compound together with 25 m0] of stirred for a further 10 minutes with decolorizing chartone, moi of Potassium Carbonate and 12 0 f coal at the same temperature and filtering is then efn'hexylbromide are heated for h urs to 55 While f t d ith th dditi f a fil i ili stirring. Subsequently the acetone is distilled off in a Di till ti at d d pressure i h ff t d i vacuum, the residue is washed several times with water order to remove excess oxalic acid diethyl e ter, 40 and recrystallization from alcohol is effected. The com- On cooling, the resulting ester amide crystallizes out P u of ula completely; melting point to 71, yield: to

By recrystallization from alcohol the colourless, pure 1 product of melting point 76 to 77 is obtained. How- 0 ever, this purification is unnecessary and the crude 45 u product may be used for reaction with a further amine,

e.g. as shown at section 111 hereof. 11. The ester amide C produced as at 1 hereof and 2-ethylaniline in molar quantities are heated for 4 hours to a bath temperature is obtained with a yield of approximately 90% in the of with the addition of a little ethereal boron tri- 50 form of white crystals of melting point 71 to 72. The fluoride as catalyst. The resulting alcohol is removed at absorption maximum in alcoholic solution is around reduced pressure (200 mm of Hg) during the reaction. 300 to 310 mu, the extinction coefficient amounts to After the reaction is complete, the resulting dark mash 13,700. At 20 the solubility in alcohol is about 16.5 is poured into a dish and allowed to cool, whereby 21 grams per litre and in benzine about 23 grams per litre. 55

T st s Constitution m .p lambda E Solubility in I ethanol i ban-zine lBLLOO 1900 2100 Table 2 (Continued) Constitution m .p lambda E .Solubility in ethanol benzine @NHCOCONH@CH 3 188490 3 5 l81+00 190 @mncoconr? 202-2o3 280 17000 150 330 @NHCOCONH@'C1 212 21 280 19800 180 c1@-Nu00c01\m@c1 297-298 280 22500 63 1,

@Niic000n1r' 197 199 300 11,300 500 1,00

l 01 OCH 3 @nacocorm-@0cn 3 1719172 290 16500 590 @micocomr@oo H 150-1 51 290 17100 320 500 @mncoo0mr@ c1 215-2l6 290 17500 390 60 OCH 3 @mncocomr@-c1 l87-l88 298 17 00 500 90 @wucoconwQ 122 12 308 16700 650 1520 OnC H O-nC 3-1 EXAMPLE A om Polyethylene is mixed in a suitable mixer at with NHCOC C) 0.2% of its weight of the compound of the formula NHCOCONH OCH 0 H and the mixture is then pressed into sheets of a thick- 65 ness of 0.25 mm.

EXAMPLE B 0.5% of the compound of the formula EXAMPLE C 3% by weight of the compound of the formula are added to a commercially available nitro lacquer. Fir wood which has been painted with this lacquer does not darken in colour on exposure to light even after a long period, whereas similarly painted pieces of fir wood with nitro lacquer not containing the above oxalamide darken in colour when similarly exposed.

EXAMPLE D Polyethylene is mixed with 0.3% of the compound of formula and 0.2% of tri-nonylphenyl phosphite at 180 and pressed into sheets of 0.2 mm thickness; the resulting structures are very well protected against light, heat and oxidation.

It is also known that certain diaryloxalamides may be used as UV light absorbers for plastics. The known compounds of this class have a remarkable UV light absorption power, but they do not have any special heat stabilization and antioxidation effect. We have now found that certain diaryloxalamides containing sulphur in the molecule do not only have the property of absorbing UV light rays, but also the ability to protect plastics from heat and against oxidative degradation.

The present invention provides sulphur containing diaryloxalamides of the formula la wherein each of R to R independently of one another, is selected from H, alkyl, aralkyl, alkaryl, al-

and n represents a Whole number of from 1 to 12 inclusive. Some preferred compounds of the formula la have the formula lb I SY X wherein X represents an alkyl radical with up to 16 carbon atoms,

Y represents an alkyl radical with up to 12 carbon atoms,

and Z represents H or CH,,, with the proviso that SY must be in the 2- or 4- position.

The compounds of formula Ia may be produced, in accordance with the present invention, by a process which is characterized in that 1 mol of oxalic acid or 1 mol of a functional derivative thereof (e.g. an ester, an ester halide or acid halide) is reacted with 1 mol of a compound of the formula Ha l R NH I15 l I R R R5 NH III 2 wherein R to R have the above meaning, in such a way that amidation of the oxalic acid or its functional derivative is effected to the greatest possible extent, and the resulting product is alkylated, when this is necessary, to give an end product of the formula la.

The compounds of the present invention are very stable against the effect of heat and protect plastics, especially polyolefins, from harmful effects of UV light rays as well as heat. They can be incorporated in the plastics in the usual way, whereupon the latter can be converted into the most varied shaped articles by pressing, extruding or spinning. Especially good effects may be obtained when the compounds of the invention are incorporated into plastics in combination with a suitable co-stabilizer, for example with a sterically hindered phenol, a phosphorus containing compound, an organic tin compound, a metal (e.g. nickel) salt, a complex metal (e.g. nickel) compound which is known to be a stabilizer for plastics. Advantageously the amount of the compound of formula la to be added to the plastics is about 0.05 to 1%, or 0.1 to 2% of a mixture of a compound of formula Ia and a co'stabilizer, both said I ranges being based on the weight of the plastics.

Examples of suitable ester halides of oxalic acid are the acid chloride or acid bromide; of the ester halides the chloride is especially suitable.

PRODUCTION EXAMPLES EXAMPLE la Production of 1-ethoxy-3-ethylthiooxalic acid bis-anilide oc n II mrcocoo 1-1 H N oc H NHCOCON'H- 2H SQZH 1. o-ethoxyaniline and oxalic acid diethyl ester are mixed in molar ratio of 1:2. Per mol of amine about 3 to 4 ml of ethereal boron trifluoride are added as catalyst and heating while stirring to 130C (bath temperature) is effected. Dissolution takes place after a short while. As ethanol reflux commences the mixture is 'put under a vacuum (about 200 mm of Hg)in order to remove ethanol and stirring is continued for a further 1% hours at the same temperature. The resulting dark brown solution is further stirred for minutes longer with decolourizing charcoal at the same temperature and then suctioned off with the addition of a filtration aid.

Subsequently excess oxalic acid diethyl ester is distilled off at reduced pressure.

On cooling, the resulting ester amide crystallizes out completely. By recrystallization from a mixture of ethanol and water (1:1) the pure product in the form of white crystals of melting point 7677C is obtained.

However, it is possible to use the crude product for the further reaction. Yield: about 90% of theory.

11. The pure ester amide produced according to l and 3-ethylthioaniline are heated in molar quantities with the addition of a little ethereal boron trifluoride for 4 hours to 170C (bath temperature). The'resulting alcohol is removed at reduced pressure (200 mm of Hg) during the reaction. After the reaction has gone to completion, the resulting dark mash is run into a dish and allowed to cool, whereby a hard mass results which is first comminuted and subsequently finely rubbed with alcohol in a trituration dish, suctioned off and washed with alcohol.

" The resulting crude 1-ethoxy-3'-ethylthiooxalic acid bis-anilide can be purified by recrystallization from benzene and melts at l06107C. Yield: (second step) about 90% of theory.

EXAMPLE 2 a Working is effected as at I in Example la, but instead of using o-ethoxyaniline o-aminophenol is used and the ester amide of the formula NHCOCOO 0 1-1 is obtained. This compound is converted according to the method stated at II in Example 1a by reaction with o-methylthioaniline to give the compound of the formula 1 mol of this compound together with 20 mol acetone, 1.5 mol potassium carbonate and 1.2 mol noctylbromide are stirred for 72 hours at 55C. By distilling off acetone, washing the residue with water and recrystallizing from isopropanol a compound of the formula is obtained with a yield of about 85% of theory. It melts at 83C.

In similar manner it is possible to produce the compounds mentioned in the following Table 3.

In this Table the following properties of the listed compounds are stated: melting point in degrees Centigrade, wave length lambda is stated in nanometers (nm) and is the wave length of the light which is absorbed most strongly.

The molar extinction coefficient, E, was determined in an alcoholic solution.

EXAMPLES OF USE I 4. A compound according to claim 1 of the formula EXAMPLE Aa In a suitable mixer there is added to polyethylene NHCOCONH 0.3% of its weight of a compound of the formula 5 NHCOCONH 7 SCH I 00 1-1 10 5. A compound according to claim 1 of the formula After the mixture has been homogenized, it is pressed to form sheets. The resulting sheets are stable against UV light rays and against heat.

EXAMPLE Ba Polypropylene is mixed at 180 with 0.5% of a compound of the formula v 6. A compound according to claim 1 of the formula C H S NHCOCONH 2O NHCOCONH and subsequently pressed into sheets. These have a 25 I OG H high light and heat stability. By simultaneously adding sterically hindered phenols, for example 2,6-di-tert.bu- 0c H tyl-4-methylphenol, or of organic phosphorus com- 2 pounds, for example diphenyl-isooctyl phosphite, the

stability to heat is increased.

Although the present invention is described herein with particular reference to specific details, it is not intended that such details shall be regarded as limitations upon the scope of the invention except insofar as included in the accompanying claims. NHCOCONH What is claimed is: I

1. A compound of the formula 7. A compound according to claim 1 of the formula l NHCOCONH /l 4 40 8. A compound according to claim 1 of the formula terc Bu'tyl wherein m represents a whole number from 1 to 8 in- I clusive, n represents a whole number from 1 to 4 inclu- C H C H sive, r represents the number 1 or 2, R, represents a hydrogen atom or an alkyl radical containing from one to four carbon atoms in at least one of the positions 4 or 9. A compound of the formula 5 of the ring, and R represents a hydrogen atom or an alkyl radical containing from one to eight carbon atoms- Is ononyl 2. A compound according to claim 1 of the formula C l-I (cert NH-C0-CO-NH- 9 9 I Nx-co-co-Nn H 3. A compound according to claim 1 of the-formula c H t 7 15 NHCOGONH -.NH-CO-CO-NH-@ I Cal-I C HS 00 E1 0 1-1 10. A compound according to claim 1 of the formula 11. A compound according to claim 1 of the formula 19. A-compound according to claim I of the formula 5 O'nCl I-I C H 11 (150-) 12. A compound according to claim l'of the formula 20. A compound according to claim 1 of the formula terc. 1 I

NHCOCONH 13. A compound according to claim 1- of the formula 21. compound according to claim 1 of the formula 15. A compound according to claim 1 of the formula 16. A compound according to claim 1 of the formula 24. A compound according to claim 1 of the formula I tert.Bu'tyl NHQOCONH NHCOCONH@'-tert Butyl C H C H CH 1 2 5 2 5 I 17. A compound according to claim 1 of the formula A 9? dccordmg to clalm 1 of the formula I 'r OC H5 CH5 26. A compound according to claim 1 of the formula Q-C H 27. A compound according to claim 1 of the formula 28. A compound of the formula 29. A sulphur containing diaryloxalamide according to claim 28 of the formula lb NHCQQQNHQ' ox SY wherein X represents an alkyl radical containing up to 16 carbon atoms,

Y represents an alkyl radical containing up to 12 carbon atoms,

and Z represents H or methyl with the proviso that the SY group must be in the 2- or 4-position.

30. A compound according to claim 28 of the formula @AIHCOCONHQ ocH sc r:

31. A compound according to claim 28 of the formula @mocomr p 00 11 SCH5 32. A compound according to claim 28 of the formula CH5 .QNHCOOONHQ 33. A compound according to claim 28 of the formula Qmzcocoma SCH 34. A compound according to claim 28 of the formula @micocolm 35. A compound according to claim 28 of the formula @rmcoco 36. A compound according to claim 28 of the formula NHCOCONH 17 OCH 37. A compound according to claim 28 of the formula @NHCOCONH 0011 38. A compound according to claim 28 of the formula @mzoooomr $011 39. A compound according to claim 28 of the formula @NHCOCONH SCH 40. A compound according to claim 28 of the formula 00 1-1 (iso) NHCOCONH scH 00 1i (iso) 41. A compound accofigig to claim 28 of the for- 47. A compound accorri g to claim 28 of the formula mula N'HCOCONHQ (n)H C -S--NH-CO-CO-NH..

C H (tert.; l B 16 55 42. A compound according to claim 28 of the for- CH mula 10 J 48. A compound according to claim 28 of the for- 1mcocomnsc mula I 4 I I OC H 43. A compound according to claim 28 of the formula SCZHS NHCOCONH 49. A compound according to claim 28 of the formula 00 H as H 2 5 4 9 a mrcocouasca 44. A compound according to claim 28 of the formula OC 'H Cl2H25s COCONH 3O 50. A compound according to claim 28 of the formula 45. A compound according to claim 28 of the formula SC H NHOOCONH I 40 O mrcocomrsc n S611 SCI-I 46. A compound according to claim 28 of the formula 52. A compound of the formula NHCOCON'H SC H SC H 

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